JP2003324214A - Light emitting module - Google Patents

Abstract

(57) [Problem] To provide a light-emitting module capable of improving heat radiation of a light-emitting component with a simple configuration and without increasing the thickness or the size too much. SOLUTION: A pair of lands 3 is provided on a surface of a wiring board 24.
3 and 34 are opposed to each other, and two wiring lines 35 and 36 are connected to lands 33 and 34, respectively. Light emitting component 2
The mounting-side external electrode 30 is connected to a lead frame to which the light-emitting element is die-bonded, and the non-mounting-side external electrode 31 is connected to a lead frame connected to the light-emitting element via a bonding wire. Then, the mounting-side external electrode 30 is joined to the land 33 with solder 37, and the non-mounting-side external electrode 31 is joined to land 34 with solder 37, and the light emitting component 23 is mounted on the wiring board 24. Light emitting component 2
The line width of the wiring line 35 to which the mounting-side external electrode 30 is soldered is larger than the line width of the wiring line 36 to which the non-mounting-side external electrode 31 is soldered.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a light emitting module in which a light emitting element is mounted on a wiring board. In particular, it relates to a light emitting module used in a surface lighting device.

[0002]

BACKGROUND ART Liquid crystal display devices are characterized by being thin and lightweight, and the demand thereof for personal computers and the like is increasing. As a result, the demand for liquid crystal display devices is increasing, but since the liquid crystal display panel itself does not emit light by itself, external light or a surface lighting device (auxiliary lighting) is required in order to visually recognize the displayed contents. Become. In addition, in recent years, liquid crystal display devices are required to save space by thinning and reducing the area, and to save power for battery driving, as the demand for mobile devices such as mobile phones and PDAs (Personal Digital Assistants) has greatly increased. Has become an important issue. Therefore, the space saving of the liquid crystal display device is supported by making the lighting device thinner.
Power saving has been achieved by adopting a light emitting diode (LED).

Therefore, in the past, in order to save power of the surface lighting device (backlight, front light, etc.), a surface lighting device is constructed by combining a light emitting module using LEDs with a light guide plate. . Figure 1 (a)
And (b) are a sectional view and a plan view showing a conventional light emitting module 1. The light emitting module 1 has a light emitting component 3 incorporating an LED 2 mounted on a wiring board 4.

As shown in FIG. 1A, the light emitting component 3 is provided with two lead frames 5 and 6, the LED 2 is mounted on the tip of one of the lead frames 5, and the other lead is mounted. The frame 6 and the LED 2 are connected by a bonding wire 7. The LED 2 is sealed with a transparent mold resin 8, and the outer surface of the transparent mold resin 8 is covered with an opaque (for example, white) mold resin 9 except for a portion corresponding to the front surface of the LED 2. Further, on the lower surface of the mold resin 9, the mounting side external electrode 1 which is electrically connected to the lead frame 5 on which the LED 2 is mounted is connected.
0 and a non-mounting side external electrode 11 that is electrically connected to the other lead frame 6 are provided.

On the other hand, in the wiring board 4, a pair of lands 13 and 14 are made to face each other on the surface of the insulating substrate 12, and two wiring lines 15 formed on the surface of the insulating substrate 12 are connected to each land 13,
It is connected to 14. Then, the mounting-side external electrode 10 and the non-mounting-side external electrode 11 are respectively connected to the land 13,
The light emitting component 3 is mounted on the wiring board 4 by soldering to the wiring board 14.

However, in such a light emitting module 1, there is a problem that the light emission brightness of the LED 2 is lowered due to heat generation (heat loss) from the LED 2. FIG. 2 is a diagram showing the relationship between the LED temperature (ambient temperature) and the brightness in a bare state in which the LED 2 is not covered with the mold resins 8 and 9. When the light emitting module 1 is driven, the temperature of the LED 2 gradually rises due to the heat generation of the LED 2, and as a result, the emission brightness of the LED 2 gradually decreases as shown in FIG.

Furthermore, as the temperature of the light emitting component 3 rises, the transmittance of the transparent molding resin 8 decreases, so LE
There is a problem that the ratio of the light emitted from the front surface of the light emitting component 3 in the light emitted in D2 decreases, and the light utilization efficiency decreases. FIG. 3 is a diagram showing the relationship between the LED temperature (ambient temperature) and the brightness when the LED 2 is covered with the mold resins 8 and 9 (the units of brightness on the vertical axis are the same as those in FIG. 2). is there. Comparing FIG. 3 and FIG. 2, the LED
In the case of FIG. 3 in which 2 is covered with the mold resins 8 and 9, the decrease in brightness is more remarkable, but this is because the transparent mold resin 8 gradually deteriorates when exposed to high temperatures for a long time (transparency decreases. This is because the transmittance is lowered.

Therefore, in the conventional light emitting module shown in FIG. 4, the heat radiation means is provided to prevent the temperature of the light emitting module from rising. In this light emitting module 16, as shown in FIGS. 4A and 4B, the dummy wiring 17 is extended from the wiring line 15 on the side connected to the land 14, and a metal is attached to the land 18 provided at the tip of the dummy wiring 17. The heat dissipation plate 19 made of a frame is soldered or riveted, and is bent toward the upper surface side of the wiring board 4 so that the heat dissipation plate 19 takes a space and does not get in the way.

In such a heat radiating means, the heat generated in the light emitting component 3 is radiated from the heat radiating plate 19 through the dummy wiring 17 and the land 18. However, in such a structure, there is a problem that the area or thickness of the light emitting module 16 is increased due to the heat dissipation plate 19, and the space for providing the light emitting module 16 is increased. Further, in such a light emitting module 16, after mounting the light emitting component 3, the heat radiating plate 19 has to be bent, which causes a problem that the number of steps for manufacturing the light emitting module 16 increases.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the problems of the above-described conventional example, and an object thereof is to improve heat dissipation of a light emitting component with a simple structure by devising a wiring board. Another object of the present invention is to provide a light emitting module that can be manufactured. Another object of the present invention is to easily attach the heat sink without bending it.
Moreover, it is to provide a light-emitting module that can realize space saving.

A first light emitting module according to the present invention is a light emitting module in which a light emitting element is mounted on a wiring board,
It is characterized in that a wiring portion formed on the wiring board and connected to the light emitting element has a heat radiation function. Here, the wiring portion is not limited to the wiring line,
It is a broad concept that includes lands, via holes, through holes, and wiring inside wiring boards. The first light emitting module is the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, the fifth embodiment, and the seventh embodiment in the embodiments of the invention described later. It corresponds to the embodiment and the ninth embodiment.

As a method of providing a heat radiation function to the wiring portion, a method of widening the wiring portion, a method of increasing the area of the wiring portion, a method of increasing the thickness of the wiring portion, and a method of increasing the volume of the wiring portion are provided. There are a method of using a material having high thermal conductivity for the wiring portion, a method of adding a heat sink to the wiring portion, and the like. In particular, in the method of increasing the area of the wiring part,
It is desirable that the total area of the wiring portion is 50% or more of the area of the wiring board.

In the first light emitting module, since the wiring portion formed on the wiring board has a heat radiation function, the heat generated by the light emitting element is radiated through the wiring portion of the wiring board, and the light emitting element is emitted. It is possible to suppress the temperature rise. Therefore, according to the first light emitting module, it is possible to suppress the temperature rise of the light emitting module and prevent the luminance of the light emitting module from decreasing.

Further, in the first light emitting module, when the wiring board is manufactured, since the wiring portion may be provided so as to give the heat radiation function, the heat radiation function can be easily given. Further, since the wiring portion has a heat radiation function, the light emitting module including the heat radiation portion can be downsized.

In the embodiment of the first light emitting module according to the present invention, among the wiring portions formed on the wiring board, the wiring connected to the light emitting element through a path having a relatively small thermal resistance. The heat dissipation of the part is made higher than that of the wiring part connected to the light emitting element via a path having a relatively large thermal resistance. Here, the wiring portion connected to the light emitting element via a path having a relatively small thermal resistance (referred to as a low thermal resistance side wiring portion) is, for example, a wiring connected to the lead frame side to which the light emitting element is die-bonded. It is a part. Further, the wiring portion connected to the light emitting element via a path having a relatively large thermal resistance (referred to as a high thermal resistance side wiring portion) is, for example, the lead frame side connected to the light emitting element via a bonding wire. It is a wiring part to be connected.

The heat radiation property of the wiring portion connected to the light emitting element via the path having a relatively small thermal resistance is higher than that of the wiring portion connected to the light emitting element via the path having a relatively large thermal resistance. To increase the width, the width of the low thermal resistance side wiring part is made wider than the width of the high thermal resistance side wiring part, the area of the low thermal resistance side wiring part is made larger than the high thermal resistance side wiring part, and the low thermal resistance The method of making the thickness of the side wiring part larger than the thickness of the high thermal resistance side wiring part, the method of making the volume of the low thermal resistance side wiring part larger than the volume of the high thermal resistance side wiring part, and the material of the low thermal resistance side wiring part having high thermal resistance There are a method of using a material having higher thermal conductivity than a material of the side wiring portion, a method of adding a heat dissipation plate only to the low thermal resistance side wiring portion, and the like.

According to such an embodiment, a large amount of heat generated in the light emitting element flows in the wiring portion on the low thermal resistance side, so that the heat radiation property of the wiring portion on the low thermal resistance side is made higher to generate the light emitting element. The generated heat can be efficiently dissipated, and the effect of preventing the temperature rise of the light emitting element can be further enhanced. In particular, this embodiment is advantageous when the area where the low thermal resistance side wiring portion and the high thermal resistance side wiring portion can be provided is limited, or when the cost of the light emitting module is desired to be suppressed.

In another embodiment of the first light emitting module according to the present invention, the surface of the wiring board is covered with a layer for preventing solder outflow, and the entire opening formed in the layer for solder outflow prevention is the above-mentioned. The wiring portion is exposed, and the light emitting element is connected to the exposed surface of the wiring portion exposed from the solder outflow prevention layer.

According to such an embodiment, the light emitting element or the like can be mounted based on the position of the opening (or the wiring portion exposed from the opening) formed in the layer for preventing the solder outflow. The size of the wiring portion itself is not restricted by the mounting accuracy. Therefore, the area of the wiring portion can be increased to enhance the heat dissipation of the wiring portion, and the light emitting module having excellent heat dissipation and mountability can be realized.

A second light emitting module according to the present invention is a light emitting module in which a light emitting element is mounted on a wiring board,
A heat dissipation portion is provided inside the wiring board. The second light emitting module corresponds to a seventh embodiment in the embodiments of the invention described below.

In the second light emitting module, since the heat dissipation portion having good thermal conductivity is provided inside the wiring board,
The heat generated in the light emitting element is radiated from the heat radiating portion inside the wiring board, and the temperature rise of the light emitting element can be suppressed. Further, when the heat dissipation portion is provided inside the wiring board, since a plurality of plate-shaped heat dissipation portions can be provided, a high heat dissipation effect can be obtained. Therefore, according to the second light emitting module, it is possible to suppress the temperature rise of the light emitting module and prevent the luminance of the light emitting module from decreasing.

Further, in the second light emitting module, since the heat dissipation portion may be provided inside the wiring board in the process of manufacturing the wiring board, the heat dissipation portion can be easily provided.
Further, since the heat dissipation portion is provided inside the wiring board, the light emitting module including the heat dissipation portion can be downsized.

A third light emitting module according to the present invention is a light emitting module in which a light emitting element is mounted on a wiring board,
It is characterized in that a heat dissipation portion is provided so as to be in close contact with the back surface of the wiring board. The third light emitting module corresponds to a sixth embodiment in the embodiments of the invention described below.

In the third light emitting module, since the heat dissipation portion having good thermal conductivity is provided on the back surface of the wiring board,
The heat generated in the light emitting element is radiated from the heat radiating portion on the back surface of the wiring board, and the temperature rise of the light emitting element can be suppressed. In addition, except for the double-sided wiring board and the like, the heat dissipation portion can be provided on almost the entire back surface of the wiring board, so that a high heat dissipation effect can be obtained. Therefore, according to the third light emitting module, it is possible to prevent the temperature of the light emitting module from rising and prevent the luminance of the light emitting module from decreasing.

Further, in the third light emitting module, since it is only necessary to attach the heat dissipation portion to the back surface of the wiring board, the heat dissipation portion can be easily provided. Further, since the heat dissipation portion (for example, a plate-shaped heat dissipation portion) is provided so as to be in close contact with the back surface of the wiring board, the light emitting module including the heat dissipation portion can be downsized.

A fourth light emitting module according to the present invention is a light emitting module in which a light emitting element sealed in a package is mounted on a wiring board, wherein a heat radiating portion is attached to the surface of the package. The fourth light emitting module corresponds to the eighth embodiment in the embodiments of the invention described below.

In the fourth light emitting module, since the heat radiating portion having good thermal conductivity is attached to the package enclosing the light emitting element, the heat generated in the light emitting element is radiated through the package. It is possible to suppress the temperature rise of the light emitting element by radiating heat from. Therefore, it is possible to prevent a decrease in the brightness of the light emitting module. Further, since the heat dissipation part can be easily attached to the package using an adhesive or the like, the heat dissipation part can be easily attached. Further, unlike the conventional example, no space is created between the package and the heat radiating portion, so that the light emitting module including the heat radiating portion can be downsized.

The above-described components of the present invention can be combined as much as possible.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 5 is a front view showing the structure of a light emitting module according to an embodiment of the present invention, and FIG. 6 is a plan view thereof. This light emitting module 21
Is used as a light source of a surface lighting device used as, for example, a backlight of a liquid crystal display device or a front light of a reflective liquid crystal display device.

The light emitting module 21 has a light emitting component 23 mounted on a wiring board 24 such as a printed wiring board or a flexible board. The light emitting component 23 includes a light emitting element 22 such as an LED in a package,
As shown in FIG. 5, two lead frames 2
5 and 26, the light emitting element 22 is mounted on the tip of the mounting side lead frame 25, and the non-mounting side lead frame 26
The light emitting element 22 and the light emitting element 22 are electrically connected by a bonding wire 27. At least a portion of the light emitting element 22 is sealed with a transparent molding resin 28, and the transparent molding resin 2 is excluded except for a portion corresponding to the front surface of the light emitting element 22.
The outer surface of 8 is an opaque (for example, white) molding resin 29.
Is covered by. Further, on the lower surface of the mold resin 29, a mounting side external electrode 30 that is in conduction with the mounting side lead frame 25 on which the light emitting element 22 is mounted and a non-mounting side external electrode 31 that is in conduction with the non-mounting side lead frame 26 are provided. Has been.

On the other hand, in the wiring board 24, a pair of lands 33, 34 are made to face each other on the surface of an insulating substrate 32 such as a flexible substrate or a glass epoxy resin substrate, and two wirings made of Cu or the like are formed on the surface of the insulating substrate 32. The lines 35 and 36 are connected to the lands 33 and 34, respectively. Then, the mounting side external electrode 30 is joined to the land 33 with the solder 37, and the non-mounting side external electrode 31 is joined to the land 34 with the solder 37 to mount the light emitting component 23 on the wiring board 24. Here, the line width of the wiring line 35 on the side where the mounting side external electrode 30 of the light emitting component 23 is soldered is larger than the line width of the wiring line 36 on the side where the non-mounting side external electrode 31 is soldered. It is getting bigger. In particular, it is desirable that the line width of the wiring line 35 be as wide as possible within the width of the wiring board 24.

In this light emitting module 21, since the width of the wiring line 35 is wide, the wiring line 35
The heat generated by the light emitting component 23 is conducted to the wiring line 35, and the heat radiation plate function can be provided to the wiring line 3
Heat is radiated from 5 to the air. Therefore, according to such a heat dissipation method, an extra heat dissipation component is not required, and the heat dissipation component does not increase the size of the light emitting module 21, thus saving space in a limited space. The heat dissipation of the light emitting module 21 can be improved while maintaining the above.

Of the external electrodes of the light emitting component 23, the mounting side external electrode 30 is directly connected to the mounting side lead frame 25 on which the light emitting element 22 is mounted, but the non-mounting side external electrode 31 is the bonding wire 27 and the bonding wire 27. Since it is connected to the light emitting element 22 via the non-mounting side lead frame 26, the heat of the light emitting element 22 is transferred to the mounting side external electrode 30 and the temperature easily rises, but the light emitting element is connected to the non-mounting side external electrode 31. The heat of 22 is difficult to transfer. In the light emitting module 21 of the present embodiment, since the width of the wiring line 35 on the side where the mounting side external electrode 30 is soldered is wide, the heat generated in the light emitting element 22 can be efficiently dissipated, The temperature rise of the light emitting element 22 or the light emitting component 23 can be effectively suppressed. Therefore, according to the light emitting module 21 of the present invention, it is possible to prevent a decrease in the brightness of the light emitting element 22 and a decrease in the transmittance of the molding resin 28 due to a temperature rise, and to obtain a small size and high performance light emitting module 21.

FIG. 7 is a diagram comparing the heat dissipation of the conventional light emitting module 1 having the structure shown in FIG. 1 and the light emitting module 21 according to the present embodiment shown in FIGS. 5 and 6. Line A1 of FIG. 7 shows the temperature rise of the conventional example, line B1 shows the temperature rise of the light emitting module 21 according to the embodiment, the horizontal axis of FIG. 7 shows the current IF flowing through the light emitting element 22, and the vertical axis. Represents the temperature rise (temperature difference from room temperature) Δt. Here, in the sample of the conventional example used for the test, the width of the wiring board 4 was 3 mm, and the line width of both wiring lines 15 was 0.2 mm. In the sample of the embodiment of the present invention used for the test, the width of the wiring board 24 was 3 mm, the width of the wiring line 35 on the mounting side was 2 mm, and the width of the wiring line 36 on the non-mounting side was 0.2 mm. As can be seen from FIG. 7, with the same energizing current, the light emitting module 21 of the present invention can suppress the temperature increase as compared with the light emitting module 1 of the conventional example, and the difference in the temperature increase is the energizing current value IF. Becomes larger as becomes larger.

FIG. 8 is also a diagram showing a comparison of luminance current characteristics of the light emitting module of the conventional example (FIG. 1) and the light emitting module of the present embodiment (FIGS. 5 and 6). The horizontal axis of FIG. 8 indicates the current I flowing through the light emitting element.
F is shown, and the vertical axis represents the luminance of each light emitting module. Here, the black circle mark (●) represents the brightness of the light emitting module 21 of the present embodiment, and the black square mark (■).
Represents the brightness of the conventional light emitting module 1. As shown in FIG. 7, the light emitting module 21 of the present invention can suppress the temperature rise as compared with the conventional example. Therefore, if the current value is the same, the brightness is increased accordingly.

FIG. 9 shows the relationship between the ratio S2 / S1 of the wiring area S2 of the mounting side wiring line 35 and the wiring area S1 of the non-mounting side and the temperature rise Δt of the light emitting component 23 (for the light emitting element 22). When a current of 30 mA is applied). According to FIG. 9, it can be seen that the temperature increase Δt decreases as the area of the wiring line 35 on the mounting side increases and the area ratio S2 / S1 increases.

FIG. 10 shows a comparison of the heat dissipation characteristics between the case where only the width of the wiring line 35 on the side connecting the mounting side external electrode 30 is widened and the case where both wiring lines 35 and 36 are widened. It is a figure. The horizontal axis of FIG. 10 represents the current IF flowing through the light emitting element, and the vertical axis represents the temperature rise (temperature difference from room temperature) Δt. In the thick solid line in FIG. 10, only the width of the wiring line 35 on the side to which the mounting side external electrode 30 is connected is increased (the width of the wiring line 35 is 3
mm, and the width of the wiring line 36 is 0.2 mm), the thin broken line in FIG. 10 shows a wide width of both wiring lines 35 and 36 (the width of the wiring line 35 is 3 mm, This shows the temperature rise when the width of the wiring line 36 is 3 mm). As is clear from FIG. 10, the wiring line 3 on the side to which the mounting side external electrode 30 is connected
Even if only 5 is widened or both wirings 35 and 36 are widened, there is almost no difference in the temperature rise of the light emitting module.
Therefore, in consideration of the mounting space and cost, it is preferable to widen only the wiring line 35 on the side to which the mounting side external electrode 30 is connected.

Further, the light emitting module 21 of the present invention does not require a heat sink as in the conventional example shown in FIG. 4, so that the space saving of the light emitting module 21 can be achieved. Further, in the light emitting module 16 of the conventional example, attention is paid to the difference in heat generation amount between the non-mounting side external electrode 11 connected to the mounting side external electrode 10 on the side where the light emitting element (LED) is mounted via the bonding wire. The dummy wiring 1 in which the non-mounting side external electrode 11 is connected to the heat sink 19
It was connected to the land 14 on the side where 7 came out. As a result, heat is dissipated on the side that generates less heat. On the other hand, in the light emitting module 21 of the present invention, since the mounting side external electrode 30 on the side where the light emitting element 22 is mounted is connected to the wide wiring line 35, the heat radiating means is provided on the side that generates a large amount of heat. It was possible to provide heat dissipation effectively.

(Second Embodiment) FIGS. 11A and 11B show a light emitting module 4 according to another embodiment of the present invention.
2A and 2B are a plan view and a cross-sectional view showing the structure of FIG. In this embodiment, the volume of the wiring portion on which the light emitting element 22 is mounted and the volume of the wiring portion on the non-mounting side are made different, and the volume of the wiring portion on the mounting side is made larger than that on the non-mounting side to dissipate heat from the light emitting module 41. It has good sex. Light emitting module 4 shown in FIG.
In No. 1, Cu on the side to which the mounting side external electrode 30 is connected
The land 33 made of copper is made thicker than the land 34 made of Cu on the side to which the non-mounting side external electrode 31 is connected. However, in consideration of mounting the light emitting component 23, the upper surface of the land 33 and the upper surface of the land 34 have the same height.

According to such an embodiment, the land 33 having a large thickness acts as a heat dissipation plate, and the light emitting element 22.
The mounting-side external electrode 30 connected to the mounting-side lead frame 25 on which is mounted is connected to the land 33 having a large volume, so that the heat generated in the light-emitting element 22 is efficiently dissipated, and The temperature rise can be suppressed. Moreover, the light emitting module 41 does not become large by improving the heat dissipation.

FIG. 12 shows a conventional light emitting module 1 (FIG. 1).
FIG. 12 is a diagram comparing the heat dissipation properties of the light emitting module 41 (FIG. 11) according to the present embodiment. The line A2 in FIG. 12 shows the temperature rise of the conventional example, the line B2 shows the temperature rise of the light emitting module 41 according to the embodiment, the horizontal axis of FIG. 12 represents the current IF flowing in the light emitting element 22, and the vertical axis. Represents the temperature rise (temperature difference from room temperature) Δt. Figure 1
As can be seen from FIG. 2, in the light emitting module 41 of the present invention, the temperature rise can be suppressed as compared with the light emitting module 1 of the conventional example, and the difference in the temperature rise becomes more remarkable as the energization current value IF increases. .

Although the thickness of the land is different between the mounting side and the non-mounting side here, the thickness of the wiring line may be larger on the mounting side than on the non-mounting side.

(Third Embodiment) Further, the light emitting module 42 shown in FIG. 13 is a sectional view showing still another embodiment in which the volume of the land is different between the mounting side and the non-mounting side. In the light emitting module 42, the wiring line 3
Land fittings are attached to the upper surface of the end portion of 5 and the upper surface of the end portion of the wiring line 36 with rivets 43 or the like to form lands 44 and 45, respectively. Here, land 44, 4
5 is formed by a U-shaped metal fitting, the land 44 on the side for soldering the mounting side external electrode 30 is formed by a metal fitting having a relatively large thickness, and the land 44 for soldering the non-mounting side external electrode 31 is formed. By forming the metal fitting 45 having a relatively small thickness, the lands 44 and 45 have different volumes so that the land 44 on the mounting side has good heat dissipation.

Therefore, also in this embodiment, the heat generated in the light emitting element 22 can be conducted from the mounting side external electrode 30 to the land 44 and can be efficiently radiated by the land 44, and the temperature rise of the light emitting element 22 can be effectively performed. Can be suppressed. Further, according to this embodiment, the mounting space of the light emitting module 42 may be slightly larger than that of the embodiment of FIG. 11, but the light emitting module 42 is smaller than that of the conventional example shown in FIG. To realize space saving.

(Fourth Embodiment) FIG. 14 is a sectional view showing the structure of a light emitting module 46 according to still another embodiment of the present invention. In the light emitting module 46, a material having different thermal conductivity is used for the wiring portion on which the light emitting element 22 is mounted and the wiring portion for the non-mounting side. In the light emitting module 46 shown in FIG. 14, the land 33 on the side to which the mounting side external electrode 30 is connected is formed of Au, and the land 34 on the side to which the non-mounting side external electrode 31 is connected is formed of Cu.

According to such an embodiment, since the mounting side external electrode 30 which generates a large amount of heat is connected to the land 33 made of Au which has a good thermal conductivity, the heat generated in the light emitting element 22 is transferred to the land 33. Efficiently radiates heat from the
The temperature rise of 3 can be suppressed. Moreover, since the non-mounting side external electrode 31 is formed of an inexpensive metal such as Cu, it is possible to suppress the cost increase of the light emitting module 46.

(Fifth Embodiment) FIG. 15 is a sectional view showing the structure of a light emitting module 47 according to still another embodiment of the present invention. In this light emitting module 47, the heat dissipation plate 48 is previously attached only to the land 33 on the side to which the mounting side external electrode 30 is connected. The heat dissipation plate 48 is formed of a material having a good thermal conductivity such as a copper plate, a graphite sheet, or a high thermal conductivity silicone sheet.

According to such an embodiment, the land 3 having the heat dissipation plate 48 is mounted on the mounting side external electrode 30 which generates a large amount of heat.
3, the heat generated by the light emitting element 22 can be efficiently radiated from the land 33, and the temperature rise of the light emitting component 23 can be suppressed. Moreover, since the heat sink 48 is provided only on one land 33, the land 3 on both sides is
Compared with the case where the heat radiation plates are provided on the parts 3 and 34, the number of assembling steps can be reduced, the component cost can be saved, and the space of the light emitting module 47 can be saved.

(Sixth Embodiment) FIG. 16 is a front view showing the structure of a light emitting module 49 according to still another embodiment of the present invention. Light emitting module 49 according to this embodiment
Then, the heat dissipation plate 50 is attached so as to be in close contact with the entire back surface of the insulating substrate 32 that constitutes the wiring substrate 24. As the heat sink 50, a copper plate, a graphite sheet,
It is made of a material having a good thermal conductivity such as a high thermal conductivity silicone sheet.

According to this embodiment, the heat generated in the light emitting component 23 passes through the insulating substrate 32 and the heat sink 50 on the back surface.
And the heat is dissipated from the entire surface of the heat sink 50 into the air. Therefore, it is desirable that the insulating substrate 32 be as thin as possible within the limit of ensuring electrical insulation between the front surface side and the back surface side.

According to this embodiment, since the heat dissipation plate 50 is attached to the back surface of the wiring board 24, the size of the light emitting module 49 hardly increases. Further, since the heat dissipation plate 50 can be provided on the entire back surface of the wiring board 24, a large heat dissipation area can be obtained. Therefore, it is possible to efficiently suppress the temperature rise of the light emitting component 23 while maintaining the space saving of the light emitting module 49.

FIG. 17 shows a conventional light emitting module 1 (FIG. 1).
FIG. 17 is a diagram comparing the heat dissipation properties of the light emitting module 49 (FIG. 16) according to the present embodiment. The line A3 in FIG. 17 shows the temperature rise of the conventional example, the line B3 shows the temperature rise of the light emitting module 49 according to the embodiment, the horizontal axis of FIG. 12 shows the current IF flowing in the light emitting element 22, and the vertical axis. Represents the temperature rise (temperature difference from room temperature) Δt. Figure 1
As can be seen from FIG. 7, in the light emitting module 49 of the present invention, the temperature rise can be suppressed as compared with the light emitting module 1 of the conventional example, and the difference in the temperature rise becomes more remarkable as the energizing current value IF increases. .

(Seventh Embodiment) FIG. 18 is a sectional view showing the structure of a light emitting module 51 according to still another embodiment of the present invention. Light emitting module 51 according to this embodiment
Then, the wiring board 24 has a multilayer structure of the insulating layer 52 and the heat conduction layer 53, and the land 33 to which the mounting side external electrode 30 is connected via the via hole (or through hole) 54 provided in the wiring board 24. And each heat conduction layer 53 are electrically connected. The heat conductive layer 53 is formed of a material having a good heat conductivity such as a copper plate, a graphite sheet, or a high heat conductive silicone sheet. According to this embodiment,
The heat generated in the light emitting component 23 is conducted from the land 33 to each heat conductive layer 53 through the via hole 54 and is radiated from the entire wiring board 24 to the air.

According to this embodiment, since the heat conduction layer 53 is formed by forming the wiring board 24 into multiple layers, the size of the light emitting module 49 hardly increases. Further, since the heat dissipation plate 50 can be provided on the entire wiring board 24, a large heat dissipation area can be obtained. Therefore, it is possible to efficiently suppress the temperature rise of the light emitting component 23 while maintaining the space saving of the light emitting module 49.

(Eighth Embodiment) FIG. 19 (a) is a front view showing the structure of a light emitting module 55 according to still another embodiment of the present invention, and FIG. 19 (b) is a light emitting component to which a heat dissipation plate 56 is attached. FIG. 23 is a perspective view of 23. In the light emitting module 55 according to this embodiment, the molding resin 2 of the light emitting component 23 is used.
A heat dissipation plate 56 is attached to the upper surface of 9 with an adhesive or the like. The heat radiating plate 56 is made of a material having a good thermal conductivity such as a copper plate, a graphite sheet, and a high thermal conductive silicone sheet.

According to this embodiment, since the heat radiation plate 56 is attached to the upper surface of the light emitting component 23, the heat generated in the light emitting element 22 is radiated through the molding resins 28 and 29.
And is radiated to the air from the heat radiation plate 56. Therefore, it is possible to suppress the decrease in the brightness and the decrease in the transmittance of the mold resin 28 due to the temperature increase of the light emitting element 22. Further, if a heat dissipation plate 56 is provided on the upper surface of the light emitting component 23, the
Since there is no space between the heat radiating plate 19 and the light emitting component as in the conventional example, the size of the light emitting module 55 can be reduced accordingly. Therefore, it is possible to efficiently suppress the temperature rise of the light emitting component 23 while maintaining the space saving of the light emitting module 49.

FIG. 20 shows a conventional light emitting module 1 (FIG. 1).
It is a figure which compared the heat dissipation of the light emitting module 55 (FIG. 19) by this embodiment. The line A4 of FIG. 20 shows the temperature rise of the conventional example, the line B4 shows the temperature rise of the light emitting module 55 according to the embodiment, the horizontal axis of FIG. 12 shows the current IF flowing through the light emitting element 22, and the vertical axis. Represents the temperature rise (temperature difference from room temperature) Δt. Figure 1
As can be seen from FIG. 7, in the light emitting module 55 of the present invention, the temperature rise can be suppressed as compared with the light emitting module 1 of the conventional example, and the difference in the temperature rise becomes more remarkable as the energizing current value IF increases. .

(Ninth Embodiment) FIGS. 21A and 21B are a sectional view and a plan view showing the structure of a light emitting module 61 according to still another embodiment of the present invention. Also,
FIG. 21C is a plan view of the wiring board 24 used in the light emitting module 61. This light emitting module 6
In the light-emitting component 23 used for No. 1, the mounting-side external electrode 30 that is electrically connected to the mounting-side lead frame 25 to which the light-emitting element 22 is die-bonded is provided from the lower part of one side surface of the molding resin 29 to the lower surface, The non-mounting side external electrode 31 which is electrically connected to the non-mounting side lead frame 26 connected to the light emitting element 22 through the bonding wire 27.
Is provided from the lower portion of the other side surface of the molding resin 29 to the lower surface.

Further, in the wiring board 24 used in the light emitting module 61, as shown in FIG. 21 (c), Cu is provided on almost the entire upper surface of the insulating substrate 32 with a relatively small gap therebetween. Two wiring parts 62 and 63 are provided. Further, almost the entire surface of the insulating substrate 32 from above the wiring portions 62 and 63 is covered with a cover lay 64 made of an insulating material for preventing solder outflow, and the cover lay 64 is partially covered at the soldering position of the light emitting component 23. It is open to. The opening 65 of the cover lay 64 is accurately and accurately opened corresponding to the soldering position.

Therefore, when the light emitting component 23 is automatically mounted on the wiring board 24, the wiring portions 62, 63 exposed from the opening 65 of the cover lay 64 are used as positioning references for the wiring portion 62, Mounting side external electrode 3 on the exposed surface of 63
0 and the non-mounting side external electrode 31 are mounted on the light emitting component 23.
Then, both external electrodes 30 and 31 are soldered to the exposed surfaces of the wiring portions 62 and 63 with solder 37, respectively.

According to such a light emitting module 61,
Large-area wiring portions 62, 6 provided on the wiring board 24
Since the heat of the light emitting element 22 can be efficiently radiated from No. 3, it is possible to suppress the decrease in the brightness of the light emitting component 23. Moreover, with such a structure, the thickness and size of the light emitting module 61 do not increase, and the light emitting module 61 can be downsized and space can be saved.

On the other hand, if the wiring portions 62 and 63 themselves are made larger in this way, it becomes difficult to accurately and automatically mount the light emitting component 23 with reference to the wiring portions 62 and 63.
In this light emitting module 61, the cover lay 64 is accurately opened at the soldering position, and the wiring portion 6 is opened from the opening 65.
Since 2, 63 are exposed, by mounting the light emitting component 23 with reference to the position of the exposed surface of the wiring portions 62, 63 from the opening 6 (that is, the opening 65 itself), the light emitting component 23 can be accurately driven. Can be implemented.

FIG. 23 is a diagram showing the heat dissipation characteristics of the light emitting module 61 according to the present invention shown in FIG. 21 and the conventional light emitting module in comparison. Line A5 of FIG. 23 shows the temperature rise of the conventional example, line B5 shows the temperature rise of the light emitting module 61 according to the embodiment, the horizontal axis of FIG. 23 shows the current IF flowing through the light emitting element 22, and the vertical axis. Represents the temperature rise (temperature difference from room temperature) Δt. FIG. 23
As can be seen, in the light emitting module 61 of the present invention,
The temperature rise can be suppressed as compared with the light emitting module of the conventional example, and the difference in the temperature rise becomes more remarkable as the conduction current value IF increases. Specifically, when the energizing current value is 30 mA, the temperature rise Δt is 55 ° C. in the conventional example.
However, in the light emitting module 61 of the present embodiment, the temperature rise Δt could be reduced to 18 ° C. with the same energizing current value.

The conventional example used for comparison here has a structure as shown in FIG. FIG. 22
In the light emitting module 71 shown in (a) and (b), a sheet-like cover lay 72 having an opening 75 is formed on the surface of the insulating substrate 12 from above the wiring portions 73 and 74 formed on the insulating substrate 12. Laminating and opening 75 of cover lay 72
The soldering areas of the wiring portions 73 and 74 are exposed. However, in the conventional light emitting module 71, the opening 75 of the cover lay 72 is not accurately formed, so that the entire soldered portions of the wiring portions 73 and 74 are shown in FIG.
As shown in (b), the light emitting component 3 is mounted by exposing it from the opening 75 and using the shape of the soldered portion of the wiring portions 73 and 74 exposed inside the opening 75 as a positioning reference.
When the light emitting component 3 is mounted using the soldered portions of the wiring portions 73 and 74 as a reference for positioning like the light emitting module 71, if the wiring portions 73 and 74 are too large, the light emitting component 3 is mounted by the solder 76. Since high mounting accuracy cannot be obtained when the wiring is performed, the wiring portions 73 and 74 cannot be enlarged. Therefore, this light emitting module 7
In No. 1, as shown in FIGS. 22 (a) and 22 (b), the wiring portions 73 and 74 are comparatively small, and therefore high heat dissipation cannot be realized as described above.

On the other hand, in the present invention, the coverlay 64
By increasing the accuracy of the opening 65 of the light emitting component 23
Since the mounting accuracy of (1) is increased, the wiring portions 62, 63 can be made larger and the heat dissipation can be improved. Since high accuracy cannot be obtained by a method of pasting the cover lay 72 of the resin sheet as in the conventional case, the light emitting module 61 of the present invention uses the glass epoxy material as the cover lay material. If a glass epoxy material is used, expansion and contraction due to heat and stress can be reduced, so that the positional accuracy of the opening 65 of the coverlay 64 can be increased.

(Tenth Embodiment) FIG. 24 is a perspective view showing the structure of a surface lighting device 81 according to still another embodiment of the present invention. The surface lighting device 81 includes a light guide plate 82, a light emitting module 83 according to the present invention, and a reflection sheet 84. The light guide plate 82 is made of a transparent resin having a high refractive index such as a polycarbonate resin or a methacrylic resin, and a light incident surface 85 is formed by obliquely cutting one corner portion, and a light exit surface 86 (upper surface of the light guide plate is formed. ), A large number of diffusion patterns 87 are formed. The light emitting module 83 is arranged so as to face the light incident surface 85,
The diffusion pattern 87 of the light guide plate 82 has a light emitting module 83.
Are arranged in an arc shape with respect to the center, and the diffusion pattern 87 is relatively coarsely distributed in the vicinity of the light emitting module 83, and the diffusion pattern 87 is gradually and densely distributed as the distance from the light emitting module 83 increases. The reflection sheet 84 is made of a white resin sheet and faces the lower surface of the light guide plate 82 on which the diffusion pattern 87 is formed.

Thus, the light emitted from the light emitting module 83 enters the light guide plate 82 through the light incident surface 85, and propagates in a direction away from the light emitting module 83 while repeating total reflection on the upper and lower surfaces of the light guide plate 82. I will do it. In the middle of this, the light is totally reflected by the diffusion pattern 87, and when the light reflected by the diffusion pattern 87 enters the light emitting surface 86 at an angle smaller than the critical angle of total reflection, the light is emitted from the light emitting surface 86 to the outside. In this way, the light is uniformly emitted from almost the entire light emitting surface 86. If necessary, a prism sheet may be arranged so as to face the upper surface of the light guide plate 82.

This surface lighting device is used as a backlight in a liquid crystal display device such as a personal computer, a PDA and a mobile phone.

[0069]

INDUSTRIAL APPLICABILITY In any of the light emitting modules of the present invention, the heat generated in the light emitting element can be efficiently dissipated to suppress the temperature rise of the light emitting module and prevent the luminance of the light emitting module from decreasing. it can. Further, in any of the light emitting modules, the heat radiating means can be easily formed, and no troublesome mounting work or processing after mounting is required.
Furthermore, in any of the light emitting modules, the thickness of the light emitting module may be increased by providing the heat dissipation means,
Since it does not easily grow in size, the light emitting module having good heat dissipation can be downsized, and the mounting space can be reduced.

[Brief description of drawings]

1A and 1B are a cross-sectional view and a plan view showing a conventional light emitting module.

FIG. 2 is a diagram showing a relationship between a temperature (ambient temperature) of an LED not covered with a mold resin and brightness.

FIG. 3 is a diagram showing the relationship between the temperature (ambient temperature) of an LED covered with a mold resin and the brightness.

4A and 4B are a partially omitted plan view and a sectional view showing another conventional light emitting module having a heat radiating means.

FIG. 5 is a front view showing a structure of a light emitting module according to an embodiment of the present invention.

FIG. 6 is a plan view of the above light emitting module.

FIG. 7 is a diagram comparing heat dissipation of the conventional light emitting module and the light emitting module shown in FIGS. 5 and 6.

FIG. 8 is a diagram showing a comparison of luminance current characteristics of a conventional light emitting module and the light emitting module shown in FIGS. 5 and 6;

FIG. 9 shows a change in temperature rise Δt of a light emitting component with respect to a ratio S2 / S1 between a wiring area S2 of a mounting side wiring line and a non-mounting side wiring area S1 in the light emitting module shown in FIGS. 5 and 6. It is a figure.

FIG. 10 is a diagram showing a comparison of heat dissipation characteristics between the case where only the width of the wiring line on the side connecting the mounting side external electrodes is widened and the case where both wiring lines are widened.

11A and 11B are a plan view and a cross-sectional view showing a structure of a light emitting module according to another embodiment of the present invention.

FIG. 12 is a diagram showing a comparison of heat dissipation between the light emitting module of the conventional example and the light emitting module of FIG. 11.

FIG. 13 is a sectional view showing a structure of a light emitting module according to still another embodiment of the present invention.

FIG. 14 is a sectional view showing a structure of a light emitting module according to another embodiment of the present invention.

FIG. 15 is a sectional view showing a structure of a light emitting module according to still another embodiment of the present invention.

FIG. 16 is a front view showing a structure of a light emitting module according to still another embodiment of the present invention.

FIG. 17 is a diagram comparing heat dissipation of the light emitting module of the conventional example and the light emitting module of FIG.

FIG. 18 is a sectional view showing a structure of a light emitting module according to still another embodiment of the present invention.

19 (a) is a front view showing the structure of a light emitting module according to still another embodiment of the present invention, and FIG. 19 (b) is a perspective view of a light emitting component to which a heat dissipation plate is attached.

FIG. 20 is a diagram showing heat dissipation properties of a conventional light emitting module and the light emitting module of FIG. 19 in comparison.

21A and 21B are a cross-sectional view and a plan view of a light emitting module according to still another embodiment of the present invention, and FIG.
FIG. 3 is a plan view of a wiring board used in the light emitting module.

22A and 22B are a cross-sectional view and a plan view showing a conventional light emitting module for comparison with the light emitting module according to the above embodiment.

23 is a diagram showing heat dissipation characteristics of the light emitting module according to the present invention shown in FIG. 21 and the light emitting module of the conventional example shown in FIG.

FIG. 24 is a perspective view showing a structure of a surface lighting device according to still another embodiment of the present invention.

[Explanation of symbols]

22 Light emitting element 23 Light emitting parts 24 wiring board 25 Mounting side lead frame 26 Lead frame not mounted 27 Bonding wire 28 Mold resin 29 Mold resin 30 Mounting side external electrode 31 Non-mounting side external electrode 33, 34 land 35, 36 wiring line 82 Light guide plate 83 Light emitting module

Claims (6)

[Claims] 1. A light emitting module in which a light emitting element is mounted on a wiring board, wherein a wiring portion formed on the wiring board and connected to the light emitting element has a heat dissipation function. . 2. The heat radiation property of a wiring portion of the wiring portion formed on the wiring board, which is connected to the light emitting element through a path having a relatively small thermal resistance, The light emitting module according to claim 1, wherein the heat radiation property is higher than that of a wiring portion connected through a relatively large path. 3. The surface of the wiring board is covered with a layer for preventing solder outflow, the wiring portion is exposed in the entire opening formed in the layer for preventing solder outflow, and exposed from the layer for preventing solder outflow. The light emitting module according to claim 1, wherein the light emitting element is connected to an exposed surface of the wiring portion. 4. A light emitting module in which a light emitting element is mounted on a wiring board, wherein a heat dissipation portion is provided inside the wiring board. 5. A light emitting module in which a light emitting element is mounted on a wiring board, wherein a heat radiating portion is provided so as to be in close contact with the back surface of the wiring board. 6. A light emitting module in which a light emitting element sealed in a package is mounted on a wiring board, wherein a heat dissipation part is attached to a surface of the package.